This invention relates generally to wire bonding of integrated circuit devices and particularly to techniques for monitoring wire bonders utilized in connection with making layered packages.
Layered packages are widely utilized in the electronics industry for packaging a variety of devices. They can include laminate packages and single-layered and multi-layered packages. Exemplary laminate packages include those without leadframes such as multichip modules including the MCM-L, MCM-C, and MCM-D packages, without excluding cerdip style packages.
Wire bond machines are used to make connections between various components of layered and non-layered electronic packages. One conventional technique, known as gold ball bonding, involves applying a molten metal ball to a bond location on a die. A ceramic capillary, for example, is then pulled from the bonded ball to a second bond location on a package and a bond is then formed to a lead on the package. The wire is then ripped from the lead, leaving two metal bonds connected by a wire.
Another conventional technique, known as aluminum wedge bonding, uses a wedge that feeds a wire through a clamp. Ultrasonic energy may be used to wedge bond the aluminum wire to form the first bond. The wedge rises, forms a wire loop, moves to the second bond site and forms a second bond like the first bond. The clamp pivots away from the tool to tear the wire at the second bond.
A large number of these connections may be made between a die and a laminate package. Testing of the packaged part for a variety of defects is normally done after the packaging process is complete. Defects may arise from poor bonds, or the total absence of a bonding wire. Poor bonds may occur, for example, due to adhesion problems or due to improper deformation of the wire.
Continuity tests in packages using leadframes are relatively straightforward. Since the leadframe is effectively located in one easily accessible strata, it can readily be accessed for testing to determine whether or not good bonds are made.
Because layered packages are tested after manufacturing, the packaged devices must sometimes be discarded because the bonds were not good. Thus, it would be desirable to have a practical technique for monitoring the wire bond apparatus used to make layered packages.